The sequences featured in this family are similar to a region close to the N-terminus of yeast exportin 1 (Xpo1, Crm1, P14068). This region is found just C-terminal to an importin-beta N-terminal domain (PF03810) in many members of this family. Exportin 1 is a nuclear export receptor that interacts with leucine-rich nuclear export signal (NES) sequences, and Ran-GTP, and is involved in translocation of proteins out of the nucleus [1,2].
The exchange of macromolecules between the nucleus and cytoplasm takes place through nuclear pore complexes within the nuclear membrane. Active transport of large molecules through these pore complexes require carrier proteins, called karyopherins (importins and exportins), which shuttle between the two compartments.